WO2013/034661 describes a sensor for measuring current in a conductor without making contact to the conductor. A first and a second magnetic bar of the sensor are placed on opposite sides of a through hole of a PCB. The first and second magnetic bar are parallel. The conductor sticks through the through hole in the PCB. A measurement coil and an excitation coil are wound around the first magnetic bar. Similarly, a measurement coil and an excitation coil are wound around the second magnetic bar such that the measurement coil and the excitation coil are concentric. The excitation coils are fed by a supply so as to regularly saturate the corresponding magnetic bars. The coils are each formed by tracks in metallization layers of the PCB, connected by vias. The changes in the current in the conductor are determined by adding and subtracting the currents through the four coils.
In many cases there are one or more other conductors in the neighborhood as well carrying a current. Such a current through the one or more other conductors will also cause a current through the measurement and excitation coils and may thus lead to an imprecise measurement of the current through the measurement coil. The current through the other conductors can have the effect that current through the measurement and excitation coils is either higher or larger than the actual current in the conductor.